Ink Composition for Optoelectronic Device

ABSTRACT

The present invention relates to an ink composition for printing capable of inking materials for an optoelectronic device and directly applying the inked materials to a patterning process. More particularly, the present invention relates to a printing ink composition for manufacturing an optoelectronic device capable of direct patterning by adjusting the physical property of a core material so as to be suitable for a printing method in the manufacturing of optoelectronic devices, for example, an organic electroluminescent device or an organic thin film transistor.

TECHNICAL FIELD

The following disclosure relates to a printing ink composition directlyapplicable to a patterning process, obtained by forming materials foroptoelectronic device into ink, and more particularly, to a printing inkcomposition for fabricating optoelectronic device obtained bycontrolling physical properties of key materials for fabricatingoptoelectronic devices optoelectronic device, including organic lightemitting diodes (OLEDs) or organic thin film transistors (OTFTs), to beamenable to a printing process and to allow direct patterning.

BACKGROUND

Recently, optoelectronic device has been succeeded in commercializationand studied intensively for their scale-up and cost-efficientfabrication. Typical examples of such optoelectronic device includeorganic electroluminescent devices or organic light emitting diodes(OLEDs), which are light emitting devices using a spontaneous lightemitting phenomenon caused by coupling between electrons and holes uponthe application of electric current to a device including afluorescence- or phosphorescence-based light emitting layer between ananode and a cathode. Such OLEDs have a simple structure, are obtained bya simple process, and realize high image quality and a broad view angle.Further, they completely realize video images and high color purity, aredriven with low power consumption under a low voltage, and thus aresuitable for portable electronic appliances.

More particularly, an OLED includes an anode, a hole injection layer, ahole transfer layer, an emitting layer, an electron transfer layer, anelectron injection layer and a cathode, stacked successively on asubstrate. Herein, the anode is frequently formed of indium tin oxide(ITO) having a low surface resistance and high transmittance. Inaddition, multiple organic thin films are disposed between the twoelectrodes as described above to increase the light emitting efficiencyand lifespan. Since the organic thin films are very weak to moisture andoxygen in the air, an encapsulating film is formed on the uppermostportion of the device to increase the lifespan thereof.

Many expensive vacuum chambers are required to form such a multilayeredOLED with high efficiency and a patterning mask is also required.Moreover, processes for fabricating OLEDs have fundamental limitation inteems of low-temperature operation. For these reasons, it is difficultto scale up OLEDs in their size and to improve cost efficiency.Therefore, there has been a continuous need for developing a novelprocess to solve the above-mentioned problems.

More recently, many attempts have been made to overcome theabove-mentioned problems through the use of a printing process. Forexample, an inkjet printing process substituting for a known depositionprocess is differentiated from the deposition process in that itconsumes a low amount of materials, shows high efficiency, and allowsscale-up and low-temperature operation. Therefore, flexible substrates,such as plastics, may be used in an inkjet printing process, resultingin significant improvement in cost-efficiency. As a result, many Koreanand foreign companies and organizations have conducted active researchand development of such inkjet printing processes. It is expected thatinkjet printing technology is applied to various industrial fields,including electric/electronic, energy, display, bioindustries, etc., andcontributes to production of a wide variety of commercial products andimprovement in cost-efficiency and eco-friendly characteristics.

Inkjet printing is low-noise, low-cost and non-contact printingtechnology. Depending on ink spray modes, inkjet printing processes areclassified into continuous jet processes and drop-on-demand (DOD)processes. The continuous jet processes performs printing by controllingink direction through a change in electromagnetic field while ink issprayed continuously with a pump. The DOD processes spray ink only at adesired moment through electrical signals, and are further classifiedinto piezoelectric inkjet processes generating pressure with apiezoelectric plate that causes dynamic deformation by electricity, andthermal inkjet processes using pressure generated upon the expansion ofbubbles produced by heat.

Methods for fabricating OLEDs using such inkjet processes are disclosedin various publications, for example, in T. R. Hebner, C. C. Wu, D.Marcy, M. H. Lu and J. C. Sturm, “Ink-jet Printing of doped Polymers forOrganic Light Emitting Devices”, Applied Physics Letters, Vol. 72, No.5, pp. 519-521, 1998. The known methods frequently use polymericmaterials, such as polyvinylcarbazole or polyphenylene vinylene (PPV),but are problematic in that they cause non-uniformity of droplet sizesand degradation of optoelectrical properties as compared to otherconventional processes. This may result from the fact that the knownprocesses may not provide an ink composition for inkjet printing thathas controllable viscosity, surface tension, solubility, film uniformityafter drying, etc., suitable for inkjet processes.

It is required for an ink composition for applying key materials, suchas organic materials for light emission, electron transfer or holetransfer, of optoelectronic device, including OLEDs, to inkjet printingprocesses, to have optimized viscosity, surface tension, solubility,film uniformity after drying, etc. Those properties may affect dropletforming systems, droplet sizes and velocities under a constant pressure.For example, when using a general inkjet system for optoelectronicdevice, an optimal viscosity of ink is 5-15 cps in view of goodejectability. However, most high-efficiency and high-lifespan compoundscommercialized and used currently as key materials of OLEDs have lowsolubility and small molecular weight, and thus have difficulty incontrolling their viscosity to be suitable for inkjet printingprocesses. For this reason, various additives are used to control theviscosity and tested for ejectability. However, some additives are notremoved after drying but still remain in ink to serve as foreignmaterials, thereby adversely affecting electrical and opticalproperties, or the like. As a result, it is not possible to maintain aunique color coordination, high efficiency and long lifespan. Inaddition, it is difficult to control the solubility and molecularweights of organic materials, such as dielectrics, semiconductors andconductors, used as key materials of organic thin film transistor (OTFT)in view of physical properties required for inkjet printing.Conventional inkjet processes using various additives result indegradation of dielectric coefficient, charge transfer and conductivitydue to the impurities remaining after the fabrication of devices.

Korean Patent Laid-Open No. 2003-0058767 discloses a method forimproving the printability of an organic light emitting layer for OLEDsformed by a roll coating process. The method uses, as a solvent, amixture containing a first solvent having a solubility of 1 wt/v %, asecond solvent having a volatility of 0.1 or less and a third solventhaving a surface tension of 30 dynes/cm or less, to prevent solventevaporation before coating a substrate and to improve solubility andsurface tension. However, the above method is merely limited toimprovement in solubility characteristics of organic polymer materialsused for a specific process, does not allow selection of an adequatecombination of solvents depending on different kinds of organic polymermaterials, and have difficulty in controlling viscosity suitable for aprinting process. Therefore, the method is not applicable to variousmaterials for fabricating optoelectronic device.

As stated above, ink compositions for fabricating optoelectronic deviceaccording to the related art have difficulty in controlling viscosity,solubility and film uniformity so that the ink compositions areapplicable to printing processes, such as inkjet processes. Therefore,processes for forming films via printing of optoelectronic materialsprovided as ink have been limited to formation of certain organic lightemitting layers. As a result, there has been marked limitation inrealizing flexible optoelectronic device, and scale-up andcost-efficient fabrication thereof

DETAILED DESCRIPTION

Technical Problems

An embodiment of the present invention is directed to providing an inkcomposition for printing key materials of optoelectronic device, such asorganic light emitting diodes (OLEDs) or organic thin film transistors(OTFTs), in the form of ink, the printing ink composition including acompound with a specific structure to control the viscosity, solubilityand film uniformity of ink, wherein the compound is decomposed easily ata sufficiently low temperature and does not adversely affect thecharacteristics of the resultant optoelectronic device.

Another embodiment of the present invention is directed to applying theprinting ink composition to various key materials of optoelectronicdevice, so that it allows fabrication of flexible devices and scale-upof devices, and improves cost-efficiency.

Technical Solutions

We have conducted intensive studies to solve the technical problems, andfound that when an ammonium carbamate compound or ammonium carbonatecompound is incorporated to a printing ink composition foroptoelectronic device, such as organic light emitting device (OLED) ororganic thin film transistor (OTFT), it is possible to control theviscosity, solubility and film uniformity of ink with ease. In addition,the ammonium carbamate compound or ammonium carbonate compound usedherein is decomposed spontaneously at a sufficiently low temperature,and thus does not adversely affect the quality of the resultant device.Therefore, many compounds having excellent efficiency and lifespan,which, otherwise, are not applicable to printing ink, may be formed intoink suitable for a printing process. As a result, it is possible toprovide flexible devices, to realize scale-up of devices, and to improvecost-efficiency.

In one general aspect, there is provided a printing ink compositiondirectly applicable to a patterning process, obtained by formingmaterials for optoelectronic device into ink. More particularly, thereis provided a printing ink composition for printing key materials ofoptoelectronic device, such as OLED or OTFT, in the form of ink, theprinting ink composition including: an ammonium carbamate compoundrepresented by Chemical Formula 1, ammonium carbonate compoundrepresented by Chemical Formula 2, ammonium bicarbonate compoundrepresented by Chemical Formula 3, or a mixture thereof.

In the above Chemical Formulae 1 to 3, R₁ through R₆ is independentlyselected from hydrogen, hydroxy, C₁-C₃₀ alkoxy, C₁-C₃₀ alkyl, C₃-C₃₀cycloalkyl, C₆-C₂₀ aryl, (C₆-C₂₀)ar(C₁-C₃₀)alkyl, functionalgroup-substituted C₁-C₃₀ alkyl, functional group-substituted C₆-C₂₀aryl, heterocyclic compound, polymeric compound and a derivativethereof, wherein when R₁ through R₆ represents alkyl or aralkylnon-substituted or substituted with a functional group, carbon chain mayinclude a heteroatom selected from N, S and O, and R₁ and R₂, or R₄ andR₅ may be independently linked to each other via alkylene with orwithout a heteroatom to form a ring.

In Chemical Formulae 1 to 3, particular examples of R₁ through R₆include but are not limited to hydrogen, methyl, ethyl, propyl,isopropyl, butyl, isobutyl, amyl, hexyl, ethylhexyl, heptyl, octyl,isooctyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl, docodecyl,cyclopropyl, cyclopentyl, cyclohexyl, cholesteryl, allyl, hydroxy,methoxy, methoxyethyl, methoxypropyl, cyanoethyl, ethoxy, butoxy,hexyloxy, methoxyethoxyethyl, methoxyethoxyethoxyethyl,hexametyleneimine, morpholine, piperidine, piperazine, ethylenediamine,propylenediamine, hexamethylenediamine, triethylenediamine, pyrrole,imidazole, pyridine, carboxymethyl, trimethoxysilylpropyl,triethoxysilylpropyl, phenyl, methoxyphenyl, cyanophenyl, phenoxy,tolyl, benzyl and derivatives thereof, polymeric compounds such aspolyallylamine or polyethyleneimine and derivatives thereof.

Particular examples of the ammonium carbamate compound of ChemicalFormula 1 include at least one compound selected from the groupconsisting of ammonium carbamate, ethylammonium ethylcarbamate,isopropylammonium isopropylcarbamate, n-butylammonium n-butylcarbamate,isobutylammonium isobutylcarbamate, t-butylammonium t-butylcarbamate,2-ethylhexylammonium 2-ethylhexylcarbamate, octadecylammoniumoctadecylcarbamate, 2-methoxyethylammonium 2-methoxyethylcarbamate,2-cyano ethyl ammonium 2-cyanoethylcarbamate, dibutylammoniumdibutylcarbamate, dioctadecylammonium dioctadecylcarbamate,methyldecylammonium methyldecylcarbamate, hexamethyleneimineammoniumhexamethyleneiminecarbamate, morpholinium morpholinecarbamate,pyridinium ethylhexylcarbamate, triethylenediaminiumisopropylbicarbamate, benzylammonium benzylcarbamate,triethoxysilylpropylammonium triethoxysilylpropylcarbamate andderivatives thereof, or a mixture thereof. Particular examples of theammonium carbonate compound of Chemical Formula 2 include at least onecompound selected from the group consisting of ammonium carbonate,ethylammonium ethylcarbonate, isopropylammonium isopropylcarbonate,n-butylammonium n-butylcarbonate, isobutylammonium isobutylcarbonate,t-butylammonium t-butylcarbonate, 2-ethylhexylammonium2-ethylhexylcarbonate, 2-methoxyethylammonium 2-methoxyethylcarbonate,2-cyanoethylammonium 2-cyanoethylcarbonate, octadecylammoniumoctadecylcarbonate, dibutylammonium dibutylcarbonate,dioctadecylammonium dioctadecylcarbonate, methyldecylammoniummethyldecylcarbonate, hexamethyleneimineammoniumhexamethyleneiminecarbonate, morpholineammonium morpholinecarbonate,benzylammonium benzylcarbonate, triethoxysilylpropylammoniumtriethoxysilylpropylcarbonate, triethylenediaminium isopropylcarbonateand derivatives thereof, or a mixture thereof. Particular examples ofthe ammonium bicarbonate compound of Chemical Formula 3 include at leastone compound selected from the group consisting of ammonium bicarbonate,isopropylammonium bicarbonate, t-butylammonium bicarbonate,2-ethylhexylammonium bicarbonate, 2-methoxyethylammonium bicarbonate,2-cyanoethylammonium bicarbonate, dioctadecylammonium bicarbonate,pyridinium bicarbonate, triethylenediaminium bicarbonate and derivativesthereof, or a mixture thereof.

In the compounds represented by Chemical Formulae 1 to 3, at least oneof substituents R₁ through R₆ preferably has 1-20 carbon atoms, and morepreferably 3-20 carbon atoms in view of miscibility with organicsolvents and decomposition capability at low temperature.

The ammonium carbamate or ammonium carbonate compounds may be preparedby any one of processes known to those skilled in the art. For example,J. Am. Chem. Soc., 70, p 3865 (1948), J. Am. Chem. Soc., 73, p 1820(1951), J. Prakt. Chem., 9, p 917 (1959), J. Am. Chem. Soc., 123, p10393 (2001), Langmuir, 18, 7124 (2002), and U.S. Pat. No. 4,542,214(1985, 9, 17) disclose that such compounds may be prepared from aprimary amine, secondary amine, tertiary amine or a mixture thereof andcarbon dioxide. The preparation may be carried out under ambientpressure or increased pressure, without any solvent or in the presenceof solvent. Particular examples of the solvent that may be used includealcohols such as methanol, ethanol, isopropanol or butanol, glycols suchas ethylene glycol or glycerine, acetates such as ethyl acetate, butylacetate or carbitol acetate, ethers such as diethyl ether,tetrahydrofuran or dioxane, ketones such as methyl ethyl ketone oracetone, aliphatic hydrocarbons such as hexane or heptane, aromatichydrocarbons such as benzene or toluene, halogenated hydrocarbons suchas chloroform, methylene chloride or carbon tetrachloride, or the like.Carbon dioxide may be bubbled in a gas phase or may be provided as soliddry ice. Supercritical carbon dioxide may also be used.

In addition to the above-mentioned method, any methods for preparingammonium carbamate or ammonium carbonate derivatives may be used as longas they provide a final product with the same structure as depictedabove. In other words, there is no particular limitation in solvent,reaction temperature, concentration or catalyst, etc.

The compound represented by Chemical Formulae 1 to 3, or a mixturethereof may be used in the printing ink composition for fabricatingoptoelectronic device in any amount, as long as it provides the printingink composition with desired characteristics. Typically, the compoundmay be used in an amount of 0.01-90 wt %, preferably 0.05-90 wt %, morepreferably 0.1-70 wt %, based on the total weight of the printing inkcomposition. When the compound is used in an amount less than 0.01 wt %,it is not possible to obtain sufficient effects. On the other hand, whenthe compound is used in an amount greater than 90 wt %, it is notpossible to obtain desired physical properties after forming a film, dueto an excessive decrease in the amount of other components, includingoptoelectronic materials and solvent.

The printing ink composition for fabricating optoelectronic devicedisclosed herein may further include other additives, such as a solvent,stabilizer, dispersant, binder resin, reducing agent, surfactant,wetting agent, thixotropic agent or levelling agent, in addition to thecompound represented by Chemical Formulae 1 to 3, or a mixture thereof.

There is no particular limitation in the solvent used in the printingink composition, as long as it provides the printing ink compositionwith desired characteristics. Particular examples of the solvent thatmay be used include water, alcohols such as ethanol or methanol, glycolssuch as ethylene glycol, acetates such as methyl acetate or ethylacetate, ethers such as diethyl ether, tetrahydrofuran, anisole ormethyl anisole, ketones such as acetone, methyl ethyl ketone oracetophenone, aliphatic hydrocarbons such as hexane or heptane, aromatichydrocarbons such as benzene, toluene, xylene or tetrahydronaphthalene,halogenated hydrocarbons such as methylene chloride, chloroform, carbontetrachloride or chlorobenzene, or the like.

The printing ink composition disclosed herein includes materials forfabricating optoelectronic device. Any materials for fabricating OLEDsor OTFTs, optoelectronic functional materials, or organic materials,organic-inorganic hybrid materials or organometallic complexes usedcurrently in conventional optoelectronic device may be used herein, aslong as they are dissolved in a selected solvent. Particularly, variousstructural or functional materials, which, otherwise, are not suitablefor forming ink applicable to direct pattern printing, may be used inthe printing ink composition disclosed herein.

Particular examples of the materials for fabricating optoelectronicdevice include: polymers, such as homopolymers including polythiophenepolymers, poly-p-phenylene polymers, poly-p-phenylenevinylene polymers,polyfluorene polymers, polycyano polymers, polyaniline polymers,polyquinoline polymers, polyvinylcarbazole (PVK) polymers, orpolypyrrole polymers, and copolymers having two or more repeating units,including polyfluorenevinylene copolymers, polyspirofluorene copolymers,or polyarylaminevinylene copolymers, various polymer derivatives for usein increasing solubility, including PEDOT/PSS, electroluminescencepolymers, including green light emitting polymers (SPG-020 availablefrom Merck), or charge transfer polymer materials; and low-molecularweight materials, such as4,4′,4″-tris(N-(2-naphthyl)-N-phenylamino)-triphenylamine (2-TNATA) andderivatives thereof,4,4′,4″-tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA) andderivatives thereof,N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) andderivatives thereof, tetraphenyldiaminediphenyl (TPD) and derivativesthereof, N,N,N′,N′-tetra(2-naphthylphenyl)(1,1′-biphenyl)-4,4′-diamine(TNB) and derivatives thereof, tris(8-hydroxyquinalinato)aluminum (AlQ₃)and derivatives thereof, copper(II)phthalocyanine (CuPC) and derivativesthereof, 9,10-di(2-naphthypanthracene (ADN) and derivatives thereof,1,4-bis(2,2-diphenylvinyl)biphenyl (DPVBi) and derivatives thereof,1,3-bis[(p-tert-butyl)phenyl-1,3,4-oxadiazoyl]benzene (OXD-7) andderivatives thereof,5,12-dihydro-5,12-dimethylquino[2,3-b]acridine-7,14-dione (DMAQ) andderivatives thereof, 4,4′-(bis(9-ethyl-3-carbazovinylene)-1,1′-biphenyl(DczVBi) and derivatives thereof, arylamine-substituted distrylarylene(DAS-amine) and derivatives thereof,4-(dicyanomethylene)-2-methyl-6-(jurolidine-4-yl-vinyl)-4H-pyrane (DCM2)and derivatives thereof, 5,6,11,12-tetraphenylnaphthacene (Rubrene) andderivatives thereof, 4,4′,4″-tris(carbazole-9-yl)-triphenylamine (TCTA)and derivatives thereof, 4,4′-bis(carbazole-9-yl)biphenyl (CBP) andderivatives thereof,bis-(2-methyl-8-quinolinolato)-4-(phenolato)aluminum(III) (BAlq) andderivatives thereof,2-(4-biphenylyl)-5-(p-tert-butylphenyl)-1,3,4-oxadiazole (PBD) andderivatives thereof, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)and derivatives thereof,10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizine-11-one(C-545T) and derivatives thereof,4-(dicyanomethyl)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidine-4-yl-vinyl)-4H-pyran(DCJTB) and derivatives thereof,2,2′,2″-(1,3,5-phenylene)tris(1-phenyl-1H-benzimidazole) (TPBI) andderivatives thereof, tris[2-(2-pyridinyl)phenyl-C,N]-iridium (Ir(ppy)₃)and derivatives thereof,bis(2-(2′-benzothienyl)-pyridinato-N,C-3′)iridium(acetylacetonate)(btp₂Ir[acac]) and derivatives thereof,bis(2-(4,6-difluorophenyl)pyridinato-N,C-2′)iridium(picolinate) (Flrpic)and derivatives thereof, platinum(II)octaethylporphyrine (PtOEP) andderivatives thereof, 2,6-bis(4-carbazolstyryl)ethylhexylanisole andderivatives thereof, and other materials soluble in a selected solvent.

Typical examples of the key materials of OLEDs, including light emittingmaterials, hole injection materials, hole transfer materials, electrontransfer materials and electron injection materials, and those of OTFTs,including organic semiconductor materials, conductive polymer materialsand dielectric materials are shown in Table 1.

In addition to the key material of OLED and OTFT, other importantmaterial for use in organic optoelectronic device may also be providedin the form of ink and applied to fabrication of device with ease.Particular example of such material include photodisk material,phtochromic material, photochemical hole burning (FHB) material, liquidcrystal material, laser pigment material, linear or non-linear opticalmaterial, resist material, photosensitive material, photographicmaterial, photoconductive material, organic photovoltaic material,electroconductive material, electrochromic material, ion conductivematerial, pyroelectric material, charge transfer complex material,dielectric material, piezoelectric material, sensor material, magneticmaterial, photoelectronic functional biomaterial, or other material thatare not suitable for forming printing ink. Typical examples of suchmaterials are shown in Table 2 as their structural formulae, which maybe substituted with suitable substituents to improve the quality of adevice, including adhesion and thin film properties.

TABLE 1 Structure OLED Fluorescence polymer

Phos- phorescence polymer

Low- molecular weight host

Low- molecular weight dopant

Hole transfer materials

Electron transfer materials

OTFT p-Type

n-Type

TABLE 2 Structure Optoelectronic functional organic materials Photodiskmaterials

Photochromic materials

PHB materials

Liquid crystal materials

Laser pigments

Optical materials

Resist materials

Photosensitive materials

Photographic materials

Photoconductive materials

Charge transfer complexes

Ion conductors

Superconductors

Sensors

Electrochromic materials

Photovoltaic materials

In Table 1 and Table 2, each of n and m represents a positive integer,and R represents any substituent and particular examples of R include,but are not limited to alkyl, aryl, heteroaryl, alkoxy, alkylcarbonyl,trialkylsilylalkylcarbonyl, imine, ether, ester, nitrile, thioalkoxy,thioester, amino, vinyl, halogen atoms, or the like. As can be seen fromTables 1 and 2, materials for OLEDs or OTFTs may be provided asfluorescence materials, phosphorescence materials, charge transfermaterials, electron transfer materials, low-molecular weight materials,dendrimers, oligomer, polymers, hybrid materials, etc. In addition, suchmaterials may be used in the form of various mixtures.

The printing ink composition disclosed herein may be applied by any onecoating process selected from spin coating, roll coating, spray coating,dip coating, flow coating, doctor blade coating, dispensing, or thelike. More preferably, the printing ink composition is applied to aprinting process capable of patterning as well as coating, and suchprinting processes include inkjet printing, offset printing, gravureprinting, gravure-offset printing, flexographic printing, screenprinting, pad printing, microcontact printing, stencil printing,imprinting, or the like. the viscosity, solubility and film uniformityof ink

Beneficial Effects

The printing ink composition for optoelectronic device disclosed hereinincludes an ammonium carbamate compound or ammonium carbonate compound,which controls the viscosity of ink, the solubility of the materials foroptoelectronic device, film uniformity, etc., and is decomposedspontaneously at a sufficiently low temperature after printing, and thusdoes not adversely affect the quality of the resultant device.Therefore, many compounds having excellent efficiency and lifespan,which, otherwise, are not applicable to printing ink, may be formed intoink suitable for a printing process. As a result, it is possible toprovide flexible devices, to realize scale-up of devices, and to improvecost-efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a thermal gravimetric analysis (TGA) thermogram of thecompound obtained from Preparation Example 1.

FIG. 2 is an atomic force microscope (AFM) graph showing the surfaceroughness of a surface formed by printing the composition of Example 1.

FIG. 3 is a photographic view taken by light emission of a patternformed by printing the composition of Example 4.

DETAILED DESCRIPTION OF EMBODIMENTS

The examples will now be described. The following examples are forillustrative purposes only and not intended to limit the scope of thisdisclosure.

Preparation of Carbamate and Carbonate Compounds

Preparation Example 1 Preparation of n-butylammonium n-butylcarbamate

To a sealed and pressurized 250 mL reactor equipped with an agitator anda gas inlet, 100 g (1.367 mol) of n-butylamine is introduced and carbondioxide gas is introduced gradually thereto at room temperature toperform a reaction. As the reaction proceeds, carbon dioxide consumptiondecreases and the reaction mixture is allowed to react sufficientlyuntil carbon dioxide is not consumed any longer. In this manner, 128.85g (yield 99%, 0.677 mol) of n-butylammonium n-butyl carbamate isobtained in the form of white powder. The resultant compound ischaracterized by thermal gravimetric analysis (TGA) and the thermogramis shown in FIG. 1. As can be seen from FIG. 1, the carbamate compoundis thermally decomposed completely at a temperature lower than 120° C.

Preparation Example 2 Preparation of n-octylammonium n-octylacarbonate

To a 250 mL Schlenk flask equipped with an agitator and a gas inlet, 100g (0.774 mol) of n-octylamine and 6.97 g (0.387 mol) of purified waterare introduced, and 22 g (0.5 mol) of carbon dioxide gas is addedgradually thereto while maintaining the temperature at 30° C. or lowerby using cooling water. Then, reaction is carried out under agitationfor 2 hours. As the reaction proceeds, the viscosity of the reactionmixture increases. Finally, 119.08 g (yield 96%, 0.372 mol) ofn-octylammonium n-octylcarbonate is obtained as transparent liquid.

Preparation Example 3 Preparation of amylammonium amylbicarbonate

To a 250 mL Schlenk flask equipped with an agitator and a gas inlet, 100g (1.147 mol) of amylamine and 20.65 g (1.147 mol) of purified water areintroduced and carbon dioxide gas is introduced gradually thereto atroom temperature to perform a reaction. As the reaction proceeds, carbondioxide consumption decreases and the reaction mixture is allowed toreact sufficiently until carbon dioxide is not consumed any longer. Inthis manner, 148.95 g (yield 99%, 1.136 mol) of amylammoniumamylbicarbonate is obtained as transparent liquid.

Preparation and Characterization of Printing Ink Composition

Example 1

To a 10 mL flask equipped with an agitator, 3 g ofpoly(3,4-ethylenedioxythiophene/poly(styrene sulfonate) (PEDOP/PSS),available from Aldrich Co., 1 g of n-butylammonium n-butylcarbamateobtained from Preparation Example 1 and 3 g of ethanol (Aldrich Co.) areadded and the reaction mixture is agitated for 10 minutes at roomtemperature. Next, the reaction mixture is filtered through a 0.2μmembrane filter to provide a composition for inkjet printing. Theresultant composition is determined for its viscosity, surface tension,printability and surface roughness, and the results are shown in Table3. Inkjet printability is determined with DMP-2813 system. Evaluation ofinkjet printability includes printing the composition on a glasssubstrate to a thickness of 80 nm, drying the composition at 150° C. for10 minutes, and determining the surface roughness. As shown in FIG. 2,the surface roughness is determined by atomic force microscopy (AFM)after inkjet printing, and it is shown that the surface roughness ishigh as evidenced by an average Ra value of 1.23 nm.

Example 2

To a 20 mL flask equipped with an agitator, 0.1 g of2,6-bis(4-carbazolestyryl)-ethylhexylanisole (INKTEC Co., Ltd.), 2 g ofn-butylammonium n-butylcarbamate obtained from Preparation Example 1, 4g of methylanisole (Aldrich) and 4 g of acetophenone (Aldrich) are addedand the reaction mixture is agitated for 10 minutes at room temperature.Next, the reaction mixture is filtered through a 0.2μ membrane filter toprovide a composition for inkjet printing. The resultant composition isdetermined for its viscosity, surface tension, printability and surfaceroughness, and the results are shown in Table 3 Inkjet printability isdetermined with DMP-2813 system and evaluated in the same manner asdescribed in Example 1.

Example 3

To a 20 mL flask equipped with an agitator, 0.1 g of3,3,5,5-tetrakis(4-t-butylstyryl)-4,4-dimethoxybiphenyl (INKTEC Co.,Ltd.), 1.5 g of n-octylammonium n-octylcarbonate obtained fromPreparation Example 2, 2.5 g of toluene (Aldrich) and 6 g oftetrahydronaphthalene (Aldrich) are added and the reaction mixture isagitated for 10 minutes at room temperature. Next, the reaction mixtureis filtered through a 0.2μ, membrane filter to provide a composition forinkjet printing. The resultant composition is determined for itsviscosity, surface tension, printability and surface roughness, and theresults are shown in Table 3. Inkjet printability is determined withDMP-2813 system and evaluated in the same manner as described in Example1.

Example 4

To a 20 mL flask equipped with an agitator, 0.1 g of a green lightemitting polymer, SPG-020 (Merck), 3 g of amylammonium amylbicarbonateobtained from Preparation Example 3, 2 g of chlorobenzene (Aldrich) and5 g of tetrahydronaphthalene (Aldrich) are added and the reactionmixture is agitated for 10 minutes at room temperature. Next, thereaction mixture is filtered through a 0.2μ, membrane filter to providea composition for inkjet printing. The resultant composition isdetermined for its viscosity, surface tension, printability and surfaceroughness, and the results are shown in Table 3. Inkjet printability isdetermined with DMP-2813 system and evaluated in the same manner asdescribed in Example 1. The composition is subjected to inkjet printingto form a pattern, and the pattern is shown in the photograph of FIG. 3taken by light emission. As can be seen from FIG. 3, the patternrealizes high-quality green light emission.

Example 5

To a 20 mL flask equipped with an agitator, 0.2 g of4,4′,4″-tris(N-(2-naphthyl)-N-phenylamino)triphenylamine, 1.5 g ofn-butylammonium n-butylcarbamate obtained from Preparation Example 1, 2g of toluene (Aldrich), 2 g of chlorobenzene (Aldrich) and 3.5 g ofacetophenone (Aldrich) are added and the reaction mixture is agitatedfor 10 minutes at room temperature. Next, the reaction mixture isfiltered through a 0.2μ membrane filter to provide a composition forinkjet printing. The resultant composition is determined for itsviscosity, surface tension, printability and surface roughness, and theresults are shown in Table 3. Inkjet printability is determined withDMP-2813 system and evaluated in the same manner as described in Example1.

Example 6

To a 20 mL flask equipped with an agitator, 0.1 g of2,2′,2″-(1,3,5-phenylene)tris(1-phenyl-1H-benzimidazole), 2.5 g ofn-butylammonium n-butylcarbamate obtained from Preparation Example 1,2.5. g of toluene (Aldrich) and 5 g of acetophenone (Aldrich) are addedand the reaction mixture is agitated for 10 minutes at room temperature.Next, the reaction mixture is filtered through a 0.2 membrane filter toprovide a composition for inkjet printing. The resultant composition isdetermined for its viscosity, surface tension, printability and surfaceroughness, and the results are shown in Table 3. Inkjet printability isdetermined with DMP-2813 system and evaluated in the same manner asdescribed in Example 1.

Example 7

To a 200 mL flask equipped with an agitator, 1 g of2,6-bis(4-carbazolestyryl)-ethylhexylanisole (INKTEC Co., Ltd.), 50 g ofn-butylammonium n-butylcarbamate obtained from Preparation Example 1, 25g of methylanisole (Aldrich) and 25 g of acetophenone (Aldrich) areadded and the reaction mixture is agitated for 30 minutes at roomtemperature. Next, the reaction mixture is filtered through a 0.2μmembrane filter to provide a composition for microgravure printing. Theresultant composition is determined for its viscosity, surface tension,printability and surface roughness, and the results are shown in Table3. Evaluation of printability includes printing the composition on a PETsubstrate to a thickness of 80 nm, drying the composition at 150° C. for10 minutes, and determining the surface roughness.

Example 8

To a 200 mL flask equipped with an agitator, 30 g of PEDOT/PSS(Aldrich), 80 g of n-butylammonium n-butylcarbamate obtained fromPreparation Example 1 and 30 g of ethanol (Aldrich) are added and thereaction mixture is agitated for 30 minutes at room temperature. Next,the reaction mixture is filtered through a 0.2μ membrane filter toprovide a composition for flexographic printing. The resultantcomposition is determined for its viscosity, surface tension,printability and surface roughness, and the results are shown in Table3. Evaluation of printability includes printing the composition on a PETsubstrate to a thickness of 80 nm, drying the composition at 150° C. for10 minutes, and determining the surface roughness.

Comparative Example 1

To a 20 mL flask equipped with an agitator, 0.1 g of2,6-bis(4-carbazolestyryl)ethylhexylanisole (INKTEC Co., Ltd.), 6 g ofmethylanisole (Aldrich) and 4 g of acetophenone (Aldrich) are added andthe reaction mixture is agitated for 10 minutes at room temperature.Next, the reaction mixture is filtered through a 0.2μ membrane filter toprovide a composition for printing. The resultant composition isdetermined for its viscosity, surface tension, printability and surfaceroughness, and the results are shown in Table 3. Inkjet printability isdetermined with DMP-2813 system and evaluated in the same manner asdescribed in Example 1.

Comparative Example 2

To a 20 mL flask equipped with an agitator, 0.1 g of a green lightemitting polymer, SPG-020 (Merck), 5 g of chlorobenzene (Aldrich) and 5g of tetrahydronaphthalene (Aldrich) are added and the reaction mixtureis agitated for 10 minutes at room temperature. Next, the reactionmixture is filtered through a 0.2μ membrane filter to provide acomposition for microgavure printing. The resultant composition isdetermined for its viscosity, surface tension, printability and surfaceroughness, and the results are shown in Table 3. Evaluation ofprintability includes printing the composition on a PET substrate to athickness of 80 nm, drying the composition at 150° C. for 10 minutes,and determining the surface roughness.

TABLE 3 Surface Viscosity tension Surface (cps) (dyne/cm) Printabilityroughness Example 1 8.2 33 Good Ra: 1.23 nm Example 2 9.1 32 Good Ra:1.88 nm Comp. Ex. 1 0.9 31 Poor Ra: 4.33 nm Example 3 7.5 32 Good Ra:1.53 nm Example 4 10.6 33 Good Ra: 2.13 nm Example 5 9.4 32 Good Ra:2.53 nm Example 6 7.9 32 Good Ra: 1.64 nm Example 7 53 32 Good Ra: 2.87nm Comp. Ex. 2 4.8 32 Poor Ra: 11.37 nm Example 8 212 31 Good Ra: 3.21nm

When comparing Example 2 with Comparative Example 1 in Table 3, it canbe seen that the composition of Example 2 including n-butylammoniumn-butylcarbamate has a viscosity suitable for inkjet printing, showsexcellent printability, and provides significantly improved surfaceroughness on the surface formed after printing.

In addition, when comparing Example 7 with Comparative Example 2, thecomposition of Example 7 has higher viscosity than the composition ofComparative Example 2, shows excellent printability when applied togravure printing, and provides significantly improved surface roughness.

1. A printing ink composition for fabricating optoelectronic device,directly applicable to a patterning process by forming materials foroptoelectronic device into ink, the printing ink composition comprisinga compound selected from compounds represented by Chemical Formula 1,Chemical Formula 2 and Chemical Formula 3, and a mixture thereof in anamount of 0.01-90 wt % based on the total weight of the composition:

wherein R₁ through R₆ is independently selected from hydrogen, hydroxy,C₁-C₃₀ alkoxy, C₁-C₃₀ alkyl, C₃-C₃₀ cycloalkyl, C₆-C₂₀ aryl,(C₆-C₂₀)ar(C₁-C₃₀)alkyl, functional group-substituted C₁-C₃₀ alkyl,functional group-substituted C₆-C₂₀ aryl, heterocyclic compound,polymeric compound and a derivative thereof, wherein when R₁ through R₆represents alkyl or aralkyl non-substituted or substituted with afunctional group, carbon chain may include a heteroatom selected from N,S and O, and R₁ and R₂, or R₄ and R₅ may be independently linked to eachother via alkylene with or without a heteroatom to form a ring.
 2. Theprinting ink composition for fabricating optoelectronic device accordingto claim 1, wherein each of R₁ through R₆ is independently selected fromhydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl,hexyl, ethylhexyl, heptyl, octyl, isooctyl, nonyl, decyl, dodecyl,hexadecyl, octadecyl, docodecyl, cyclopropyl, cyclopentyl, cyclohexyl,allyl, hydroxy, methoxy, methoxyethyl, methoxypropyl, cyanoethyl,ethoxy, butoxy, hexyloxy, methoxyethoxyethyl, methoxyethoxyethoxyethyl,hexametyleneimine, morpholine, piperidine, piperazine, ethylenediamine,propylenediamine, hexamethylenediamine, triethylenediamine, pyrrole,imidazole, pyridine, carboxymethyl, trimethoxysilylpropyl,triethoxysilylpropyl, phenyl, methoxyphenyl, cyanophenyl, phenoxy,tolyl, benzyl, polyallylamine, polyethyleneamine and derivativesthereof.
 3. The printing ink composition for fabricating optoelectronicdevice according to claim 1, wherein the ammonium carbamate compoundrepresented by Chemical Formula 1 is selected from the group consistingof ammonium carbamate, ethylammonium ethylcarbamate, isopropylammoniumisopropylcarbamate, n-butylammonium n-butylcarbamate, isobutylammoniumisobutylcarbamate, t-butylammonium t-butylcarbamate,2-ethylhexylammonium 2-ethylhexylcarbamate, octadecylammoniumoctadecylcarbamate, 2-methoxyethylammonium 2-methoxyethylcarbamate,2-cyanoethylammonium 2-cyanoethylcarbamate, dibutylammoniumdibutylcarbamate, dioctadecylammonium dioctadecylcarbamate,methyldecylammonium methyldecylcarbamate, hexamethyleneimineammoniumhexamethyleneiminecarbamate, morpholinium morpholinecarbamate,pyridinium ethylhexylcarbamate, triethylenediaminiumisopropylbicarbamate, benzylammonium benzylcarbamate,triethoxysilylpropylammonium triethoxysilylpropylcarbamate andderivatives thereof, or a mixture thereof; the ammonium carbonatecompound represented by Chemical Formula 2 is selected from the groupconsisting of ammonium carbonate, ethylammonium ethylcarbonate,isopropylammonium isopropylcarbonate, n-butylammonium n-butylcarbonate,isobutylammonium isobutylcarbonate, t-butylammonium t-butylcarbonate,2-ethylhexylammonium 2-ethylhexylcarbonate, 2-methoxyethylammonium2-methoxyethylcarbonate, 2-cyanoethylammonium 2-cyanoethylcarbonate,octadecylammonium octadecylcarbonate, dibutylammonium dibutylcarbonate,dioctadecylammonium dioctadecylcarbonate, methyldecylammoniummethyldecylcarbonate, hexamethyleneimineammoniumhexamethyleneiminecarbonate, morpholineammonium morpholinecarbonate,benzylammonium benzylcarbonate, triethoxysilylpropylammoniumtriethoxysilylpropylcarbonate, triethylenediaminium isopropylcarbonateand derivatives thereof, or a mixture thereof; and the ammoniumbicarbonate compound represented by Chemical Formula 3 is selected fromthe group consisting of ammonium bicarbonate, isopropylammoniumbicarbonate, t-butylammonium bicarbonate, 2-ethylhexylammoniumbicarbonate, 2-methoxyethylammonium bicarbonate, 2-cyanoethylammoniumbicarbonate, dioctadecylammonium bicarbonate, pyridinium bicarbonate,triethylenediaminium bicarbonate and derivatives thereof, or a mixturethereof.
 4. The printing ink composition for fabricating optoelectronicdevice according to claim 1, wherein the optoelectronic device isorganic light emitting device (OLED) or organic thin film transistor(OTFT).
 5. The printing ink composition for fabricating optoelectronicdevice according to claim 1, wherein the material for optoelectronicdevice is selected from fluorescence polymer, phosphorescence polymer,host material, dopant material, hole transfer material, electrontransfer material, organic semiconductor material, photodisk material,phtochromic material, photochemical hole burning (PHB) material, liquidcrystal material, laser pigment material, optical material, resistmaterial, photosensitive material, photographic material,photoconductive material, charge transfer complexe, ion conductivematerial, superconductive material, sensor material, electrochromicmaterial, piezoelectric material, magnetic material, photoelectronicfunctional biomaterial, organic photovoltaic material, and combinationthereof.
 6. The printing ink composition for fabricating optoelectronicdevice according to claim 1, which are applied to a printing processselected from inkjet printing, offset printing, screen printing, padprinting, gravure printing, flexographic printing, stencil printing andimprinting,
 7. The printing ink composition for fabricatingoptoelectronic device according to claim 1, which further comprises atleast one component selected from a solvent, stabilizer, dispersant,binder resin, reducing agent, surfactant, wetting agent, thixotropicagent and levelling agent.